Tapping attachment for numerical control

ABSTRACT

The invention is a tapping attachment of the type having free axial float. Direct and reverse drive is provided for by way of planetary gears for driving at the same speed in direct and reverse drive. An adjustment is provided for the magnitude of the free axial float. Spring biased clutch driver members are provided for both the direct and reverse drive providing a narrow, neutral position which cooperates with the adjustment of the free axial float. The attachment accommodates itself in a number of ways to numerical or computer control.

United States Patent 1 1 Johnson 1 Feb. 27, 1973 TAPPING ATTACHMENT FOR NUMERICAL CONTROL [7 51 Inventor: Allan S. Johnson, Costa Mesa, Calif.

[73] Assignee: Tapmatic Corporation [22] Filed: April 9, 1970 21 Appl. No.: 26,894

[52 U.S.Cl. ..10/89F, 10/138,10/141H, 408/134, 408/140 51 1m.c1. ..B23ql/46,B23q5/14 [58] Field ofSearch...l0/l35,136,138, 89 F, 141 H; 74/376, 378, 379; 408/124, 132, 134, 140;

[56] References Cited UNITED STATES PATENTS 332,436 12/1885 Rathbun ..408/l24 1,915,542 6/1933 3,075,398 l/l963 Bristol .1: 3,214,773 11/1965 Benjamin et al 3,226,993 1/1966 Varback ..40s/124 3,397,588 8/1969 Johnson ..408/l32 1,127,754 2/1915 2,287,192 6/1942 Primary ExaminerCharles W. Lanham Assistant Examiner-E. M. Combs Attorneyl-Ierzig & Walsh [5 7] ABSTRACT 5 Claims, 6 Drawing Figures PAn-jrmnrm A 3,717,892

SHEET 2 DF 2 414m 5. Jam/552v TAPPING ATTACHMENT FOR NUMERICAL CONTROL SUMMARY OF THE INVENTION The invention is a tapping attachment of the type having free axial float and providing for both direct and reverse drive. Practical improvements are provided in the device as described in detail herein, particularly adapting it to numerical or computer control.

BACKGROUND OF THE INVENTION The background of the invention is exemplified in prior patents of this inventor US. Pat. Nos. 3,041,893 and 3,397,588, which are hereby incorporated herein by reference. The background patents disclose the characteristics of tapping attachments having free axial float and direct and reverse drive. US. Pat. No. 3,397,588 discloses a type of construction wherein for the direct drive there is provided a spring biased clutch driver member which functions to eliminate chattering, when the clutch engages or disengages for direct drive.

The improvements of the herein invention are adapted to realizing the objective that the attachment is capable of doing or accomplishing movements that could be accomplished by a human arm manipulating the attachment. The realization of this end is a broad objective of the invention. A number of improvements are provided in it. The drive is by way of planetary gears in such a way that the driving speed is the same in direct drive as in reverse drive. Spring biased clutch driver members are provided for both direct and reverse drive. An adjustment collar is provided on the attachment which cooperates with the tapping spindle so that the degree or magnitude of axial float can be adjusted. This adjustment in combination with the spring biased clutch driver members makes it possible to have a very narrow neutral zone or area between direct and reverse drive thereby greatly facilitating the adaption of the attachment to numerical or computer control and to the elimination of chattering or knocking both when engaging and disengaging with respect to both direct and reverse drive.

The specific nature of the improvements are described in detail hereinafter in connection with a preferred exemplary form of the invention.

In light of the foregoing, further specific objects of the invention reside in the following:

An object is to provide mechanism whereby the speed of drive in direct drive and reverse drive is the same.

Another object is to provide mechanism to eliminate chattering or knocking both with respect to direct drive and reverse drive clutching and declutching.

Another object is to provide for adjustment of the magnitude or degree of axial float.

Another object is to provide mechanism whereby after tapping, at the limit of travel, the clutch will automatically disengage to allow shifting into reverse gear.

A further object is the realization of a very simple tool of this type, even though it has the improved characteristics set forth with a very few parts subject to wear.

Another object of the invention is the realization of a simplified mechanism in that the upper part of the housing itself becomes the planetary member that is held against rotation by way of a radial arm and this is a very distinctive advantage when the mechanism is controlled by a computer.

Another object of the invention is to realize a mechanism having multiples of identical parts which are easy to fabricate and which can be fabricated by way of powdered metal processes.

A further object of the invention is to realize an attachment of this type in which it is not necessary to provide a spring clutch for reasons which will be made more clear hereinafter.

A further object is to realize a tool of this type wherein the danger of damage or breakage of the tool when operated under numerical or computer control is eliminated or greatly minimized.

Further objects and additional advantages of the invention will become apparent from the following detailed description and annexed drawings wherein:

FIG. 1 is a view of a preferred form of the tapping attachment mounted on a machine;

FIG. 2 is a cross-sectional view of the'tapping attachment of FIG. 1;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 2;

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 2;

FIG. 5 is a detail exploded view of the spring biased clutch driver members;

FIG. 6 is an exploded view of the major components of the attachment.

Referring now more in detail to the various figures of the drawing numeral 10 designates a machine tool with which the attachment may be used. It has an arbor I1 and the tapping attachment of the invention is designated generally at 12. Numeral 13 designates a radial holding arm which engages a stop rod or column 14 which will hold the body of the attachment against rotation as will be described more in detail hereinafter. Numeral l6 designates the chuck on the tapping spindle l8 and the tap itself is designated at 20.

The tool arbor 11 is threaded as shown in FIG. 2 and it engages a bore 24 in the body 26. Numeral 30 designates a cylindrical housing having a top cover or cap 32 held on by screws 34 and 36 and from which extends the radial arm 13. The housing 30 has a bore 40 and a counter bore 42. The body 26 has a portion 46 of smaller diameter and positioned within the bore 42 between housing 30 and body 26 and engaging square shoulder 50 between the parts of body 26 of different diameter, is a ball-bearing designated generally at 52 and which comprises the usual ball races and interposed balls. The parts of the attachment are shown assembled in FIG. 2 and in the cross sectional views, and the'parts are shown individually in the exploded view, FIG. 6.

The body 26 has counter bore 60 (see FIG. 6) and an extending skirt 62. It has axial ways as shown at 63 which engage with and drive the direct drive clutch driver member as will be described. The relationship of the parts may be observed by considering the exploded view FIG. 6 with the assembled view.

Numeral 68 designates a cylindrical cage member within the housing 30 which supports the planetary gears of the gear drive. This cage has a concentric cylindrical part 70 of lesser axial length which provides bearing surfaces as will be described the shafts or arbeta of the planetary drive gears. The member 70 is integral with the outer cylindrical part 74 of the cage 78 being contected thereto by the radial web 72. The outer cylindrical part 74 of the cage has in it on the inside surfaces, equally spaced from each other three axial rectangular ways as designated at 76, 78 and 80 which provide for spaces to receive the three planetary drive gears as will be described.

The three planetary drive gears are shown best in FIG. 4 as designated at 82, 84 and 85 positioned as shown between the inner and outer parts 70 and 74 of the cage 68. These gears have shafts or arbors as designated at 90, 92 and 94. The outer ends of these shafts are received in bores formed in the part 74 of the cage 76 as designated at 100, 102 and 104. The inner ends of these shafts or arbors are received in radial bores formed in the inner cylindrical member or part 70 of the cage 68 as designated at 108, 110 and 112. The cage 68 has an axial groove 120 whereby it can be keyed by way of a key to a corresponding axial groove 122 on the inside of the housing 30 to hold the cage against rotation.

The planetary gears are bevel gears and cooperating with them are two bevel drive gears including the direct drive bevel gear 126 and the reverse drive bevel gear 128. The opening in these bevel gears are of a configuration to key them to the clutch driver members. Numeral 132 designates the clutch driver member for direct drive and numeral 134 designates the clutch driver member for reverse drive. It will be observed that the clutch driver members are alike but are in in verted positions with respect to each other in the assembly. In the fabrication and production of parts as will be observed, these two parts are identical, except that part 134 does not have web 136 shown in FIG. 6, as it must slide over spindle 18, as will be referred to again presently.

The clutch driver member 132 is like the clutch driver member 85 of U.S. Pat. No. 3,397,588. It is cylindrical having an intermediate transverse web 136 as may be seen in FIG. 2. It has three angularly spaced lugs 138, 140 and 142. It has an extending skirt 144 and formed in the skirt are three equally angularly spaced pin receiving openings or cutouts, one of which may be seen at 150. (See FIG. 6) Adjacent to one side of this cutout is an axial tapered surface 152 and on the opposite side of the cutout is a tapered surface leading to the next opening or cutout as designated at 154. Inasmuch as the clutch driver member for reverse drive is identical with the clutch driver member 132 it need not be described in detail. Clutch drive member 132 engages with and is driven by body 26 as may be observed from FIG. 6.

The opening in direct drive gear 126 is in the form of a bore 158 and there are equally spaced cutouts of larger radius or diameter designated at 160, 162 and 164 configurated to accommodate or receive the lugs 138, 140 and 142 on the clutch driver member 132. Inasmuch as the bevel gear 128 for reverse drive is identical to the gear 126 it need not be described in detail. It should be observed that in the fabrication and production of the attachment these two gears being alike, reduces the total number of different parts.

FIG. 2 shows the assembled relationship of the planetary gears, the direct drive gear 126 and the direct drive clutch driver member 132.

Positioned at the end of the bore 24 in the body 26 is a disc and in between this disc and the end of the arbor 11 is a snap ring 172. The disc 170 has two spaced openings 174 and 176 and booked through these openings is a hook 180 on the end of a suspension spring 182 which has hook 184 at its opposite end which books into the end of support member 186 that extends through a ball bearing 190 in a counter bore 192 in the cylindrical end part 194 of the spindle 18, the spindle 18 having axial bore 196 through which spring 182 extends.

At the upper end of the spindle 18 are three angularly spaced radial bores in which are received radial drive pins, two of which are shown at 200 and 202 in FIG. 5. These pins are adapted to cooperate with the cutouts previously described in the direct drive clutch driver member 132 and the reverse clutch driver member 134. It is to be observed that there is a coil spring 206 positioned in the bore 60 of the body 26 between the disc 170 and the direct clutch driver member 132 whereby this member is allowed to move against this bias in the manner described in detail in the prior U.S. Pat. No. 3,397,588. Within the upper end of the drive spindle 18 there is provided bushing 210 against which the inner ends of the drive pins like 200 abut.

Referring to FIG. 6 numeral 220 designates the lower support body. In the assembled attachment the reverse clutch driver member 134 engages in the opening of the reverse drive bevel gear 128 in the same manner that the direct drive clutch driver member 132 engages in the direct clutch drive gear 126. The body 220 has another cylindrical part 222; a bore 224 and extending flange 226 which in the assembled position shown in FIG. 2 is over ball bearing 230 which is interposed between the body 220 and the housing 30. The ball bearing 230 is positioned by a snap ring 232 received in annular groove 234 in the housing 30. (See FIG. 2) The body 220 has cylindrical part 238 of smaller diameter and extending threaded cylindrical part 240 as shown. The upper cylindrical part 222 of the body 220 has three equally spaced axial grooves 244, 246 and 248 adapted to receive the radial lugs on the reverse drive clutch member 134. The body 220 has a bore 250 (see FIG. 2) and received in this bore is a cylindrical member or bushing 252 having a bore 254 and an upper counter bore 256. Retained in the counter bore 256 is coil spring 260 which corresponds to the spring 206, this being a biasing spring which biases the reverse drive clutch driver member 134 permitting it to move axially in the same way and for the same purpose as the upper clutch driver member 132 moves.

Numeral 262 designates an adjustment collar which has internally threaded bore 264, the collar being threaded on to the threaded part 240 of the body 220. This collar is in the form of a cap having an end part which has a bore 266 through which the spindle 18 extends. In operation the spindle 18 can float as described in the previous patents, being suspended by the spring 182. The amount of this float is adjustable by adjusting the position of collar 262 on the body 220, that is by way of adjusting the position of the end of the collar relative to the chuck 194 on the end of the spindle, so that the axial float may be adjusted from any maximum amount to a minimum of l/l6inch for example, depending on the size of the drive pins. Collar 262 can engage thrust bearing 263 limiting the degree of freedom of float while in direct drive.

in the light of the foregoing description and the disclosures contained in the prior patents those skilled in the art will readily understand the operation of the attachment and will fully understand and appreciate the manner in which the objective set forth in the foregoing are realized and how the attachment adapts itself to numerical or computer control. It adapts itself to all of the movements and/or manipulations that could be made with the human arm.

The tap holding spindle has the characteristic of free axial float which is limited as described in the foregoing, the axial float being like that described in the previous patents. The tap follows its own lead. No lead pressure is applied. The machine moves the machine spindle behind the lead of the tap until the desired depth is reached. The direct drive bevel gear 126 is driven from the body 26 by reason of its engagement therewith as described in the foregoing. Body 26 drives the direct drive clutch driver member 132 by reason of its engagement therewith as described. In operation, it will be understood that the attachment as it starts tapping, moves forwardly relative to the housing 30. The adjustment collar 262 can be adjusted to a spacing as between it and the chuck 194 so that when the tool reaches the limit of its travel, that is, as determined by the setting of collar 262, the drive pins such as the pins 220 will feed out of the clutch driver member 132 and this may represent movement of only one-eighth inch, for example, at which time the drive pins are then in a neutral position between the direct drive clutch drive member 132 and the reverse drive clutch driver member 134. The direct drive clutch driver member disengages without knocking or chattering as described in US. Pat. No. 3,397,588 and the reverse drive clutch driver member engages with the pins similarly without chattering or knocking because it too is cushioned by a biasing spring this being the spring 260. The neutral position of the spindle in between direct and reverse drive is very sensitive, the neutral position being very narrow. The neutral position or zone can be as narrow as half the diameter of the radial driving pins. This very significantly adapts the attachment and accommodates it to numerical or computer control in that the amount of relative axial movement of the spindle to change between direct and reverse is reduced to a minimum. lt feeds in and out at the same rate and drives at the same speed in direct and reverse drive. The collar 262 can serve the same purpose as a spring clutch which is not required in this attachment. A spring clutch is not desirable in a computer or numerical control application because this might result in holes being tapped at 3 or 4 threads and others at 5 or 6 for example, depending at what torque load the clutch started slipping. Also in an attachment with a spring clutch used in a computer or numerical control application if the tool should stall and stop rotating, and the tool is still being driven forward, the computer not knowing that the tool is not rotating or that the clutch is slipping, since the tool is still being driven forward something has to break unless other protection is built into the assembly. With the herein attachment the computer is programmed to cause the tool to tap into the hole, the specified amount. The adjustable collar 262 is adjusted with respect to the chuck on spindle so that when the tap has reached the specified depth movement of the spindle of the machine is stopped without stopping the rotation. The tap is still turning in the work and it pulls the spindle down, the small amount necessary to bring the drive pins intoneutral position after which the engagement can then be made in the manner described for reverse operation.

The foregoing disclosure is representative of a preferred form of the invention and is to be interpreted in an illustrative rather than a limiting sense, the invention to be accorded the full scope of the claims appended hereto.

I claim:

1. In a tapping attachment having a body member adapted to be rotated about an axis thereof, a tapping spindle mounted for rotation about said axis and for free axial movement along said axis relative to said body member, and positive drive clutch means for drivingly connecting said body member to said tapping spindle, the improvement comprising;

said clutch means being defined by relatively axially movable elements on said body member and tapping spindle, respectively, said elements being in mutually driving engagement throughout a range of relative axial movement and being relatively axially movable in one direction to disengage said clutch means;

biasing means normally biasing said elements to move into clutch engaging relation; and

adjustable limiting means on said attachment for predetermining the extent of axial movement of said elements in a clutch engaging direction for presetting the magnitude of relative axial movement from full clutch engagement to disengagement thereof.

2. An attachment as in claim 1 wherein the said adjustable means comprises a member threadedly adjustable relative to the body member and positionable to be engaged by the tapping spindle to limit the extent of axial movement thereof.

3. An attachment as in claim 1 wherein said clutch element on said body is movable thereon and adapted to engage the element on said spindle for direct drive, and a biasing spring acting against the direct drive clutch member on said body to allow clutching and declutching without chattering.

4. A tapping attachment as in claim 3 including reverse driving means whereby the tapping spindle is driven atthe same speed in direct drive as in reverse drive.

5. A tapping attachment as in claim 4 wherein the drive to the spindle comprises a planetary gear transmission including planetary gears and a direct drive gear and a reverse drive gear of the same size.

III III 1' III 

1. In a tapping attachment having a body member adapted to be rotated about an axis thereof, a tapping spindle mounted for rotation about said axis and for free axial movement along said axis relative to said body member, and positive drive clutch means for drivingly connecting said body member to said tapping spindle, the improvement comprising; said clutch means being defined by relatively axially movable elements on said body member and tapping spindle, respectively, said elements being in mutually driving engagement throughout a range of relative axial movement and being relatively axially movable in one direction to disengage said clutch means; biasing means normally biasing said elements to move into clutch engaging relation; and adjustable limiting means on said attachment for predetermining the extent of axial movement of said elements in a clutch engaging direction for presetting the magnitude of relative axial movement from full clutch engagement to disengagement thereof.
 2. An attachment as in claim 1 wherein the said adjustable means comprises a member threadedly adjustable relative to the body member and positionable to be engaged by the tapping spindle to limit the extent of axial movement thereof.
 3. An attachment as in claim 1 wherein said clutch element On said body is movable thereon and adapted to engage the element on said spindle for direct drive, and a biasing spring acting against the direct drive clutch member on said body to allow clutching and declutching without chattering.
 4. A tapping attachment as in claim 3 including reverse driving means whereby the tapping spindle is driven at the same speed in direct drive as in reverse drive.
 5. A tapping attachment as in claim 4 wherein the drive to the spindle comprises a planetary gear transmission including planetary gears and a direct drive gear and a reverse drive gear of the same size. 